One vertex per element, one color per generator, with an edge from x to x·s.
(3,7)(6,8)(9,10)(11,21)(12,17)(13,20)(14,19)(15,18)(16,23)(22,37)(24,35)(25,40)(26,36)(27,33)(28,31)(29,34)(30,38)(32,39) involution — undirected(2,5)(3,7)(9,11)(10,16)(12,25)(13,28)(14,23)(15,24)(17,32)(18,31)(19,35)(20,21)(22,26)(27,38)(29,39)(30,34)(33,37)(36,40) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,11)(10,16)(12,22)(13,23)(14,28)(15,24)(17,30)(18,31)(19,21)(20,35)(25,26)(27,39)(29,38)(32,34)(33,40)(36,37) involution — undirected(2,5)(6,8)(9,12,15,27)(10,17,18,33)(11,22,24,39)(13,29,14,26)(16,30,31,40)(19,36,20,34)(21,37,35,32)(23,38,28,25)(1,3,4,7)(2,6,5,8)(10,18)(16,31)(17,33)(19,20)(21,35)(30,40)(32,37)(34,36)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.